<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>渐变案例</title>
    <style>
        .letter {
            width: 600px;
            height: 800px;
            border: 1px solid black;
            margin: 0 auto;
            background-image: repeating-linear-gradient(transparent 0px, transparent 29px, gray 30px);
            background-clip: content-box;
            padding: 10px;
        }

        .ball {
            width: 200px;
            height: 200px;
            border-radius: 100%;
            background-image: radial-gradient(at 80px 80px, white, #333);
        }
    </style>
</head>

<body>
    <div class="letter">信纸</div>
    <div class="ball">球</div>
</body>

</html>